Single-storey rear extensions opening kitchens, dining and living space onto the garden — usually 30–50 m².
Rear extensions in Brent typically cost between £66,029 and £106,632 depending on size, specification and site conditions. A mid-range 40 m² project averages around £86,340. London pricing reflects higher labour rates, parking permits and tighter site access.
Most rear extensions take between 6 and 16 weeks on site, depending on scope, structural complexity and planning requirements in Greater London.
Many rear extensions fall under permitted development, but conservation areas, listed buildings and larger projects in Brent can require a full planning application. Use the cost checker to see what applies to your address.
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Disclaimer: This is an industry-informed estimate for guidance only — not a fixed quote, valuation, survey or legal advice. Figures are based on UK regional averages and the details you provided. Site-specific factors (access, ground conditions, structural surprises, planning constraints) can materially change the cost. Always confirm with a site inspection, written quotes from qualified UK tradespeople, and supplier pricing before committing to work. Build Price IQ accepts no liability for decisions made on the basis of these estimates.